In the related art, a detection method for detecting detection target particles to be detected is known. As a detection method, a method which makes use of fluorescence-labeled antibodies specifically bonded to detection target particles to be detected is known. In the method using the fluorescence-labeled antibodies, for example, a drug solution containing fluorescence-labeled antibodies specifically bonded to viruses is brought into contact with an inspection target gas so that the viruses existing in the gas are diffused into the drug solution. Thus, a mist group of the drug solution, in which the viruses are diffused, is formed and the fluorescence intensity thereof is measured. The viruses are detected depending on the fluorescence intensity (see, e.g., International Publication No. 2012/056641).